gitea-adminandClaude Fable 5.1
8cac4370bf
AliasRegistry and RemoteRegistry duplicated the lock-file, read-modify- write and atomic-replace logic almost line for line. Move it into a generic JsonRegistry base; each registry now only declares its error type, empty value, parser and serializer. Behaviour, file format, permissions and the corrupt-file guarantee are unchanged. Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
97 lines
3.3 KiB
Python
97 lines
3.3 KiB
Python
"""Locked, atomically replaced JSON files for the small per-user registries."""
|
|
from __future__ import annotations
|
|
|
|
import fcntl
|
|
import json
|
|
import os
|
|
from pathlib import Path
|
|
import tempfile
|
|
from typing import Callable, Generic, TypeVar
|
|
|
|
|
|
Value = TypeVar("Value")
|
|
Outcome = TypeVar("Outcome")
|
|
|
|
|
|
class JsonRegistry(Generic[Value]):
|
|
"""A private JSON file updated under an exclusive lock.
|
|
|
|
Subclasses provide the user-facing error type and the mapping between the
|
|
stored payload and a Python value. Every update reads, modifies and writes
|
|
under the lock so concurrent Hub processes cannot lose each other's
|
|
changes, the file is replaced atomically with mode 0600, and a corrupt
|
|
file is never overwritten.
|
|
"""
|
|
|
|
error_type: type[RuntimeError] = RuntimeError
|
|
|
|
def __init__(self, path: Path) -> None:
|
|
self.path = path
|
|
|
|
@property
|
|
def lock_path(self) -> Path:
|
|
return self.path.with_name(f".{self.path.name}.lock")
|
|
|
|
def _empty(self) -> Value:
|
|
raise NotImplementedError
|
|
|
|
def _parse(self, payload: object) -> Value:
|
|
raise NotImplementedError
|
|
|
|
def _serialize(self, value: Value) -> object:
|
|
raise NotImplementedError
|
|
|
|
def load(self) -> Value:
|
|
if not self.path.exists():
|
|
return self._empty()
|
|
try:
|
|
payload = json.loads(self.path.read_text(encoding="utf-8"))
|
|
except (OSError, json.JSONDecodeError) as error:
|
|
raise self.error_type(f"cannot read {self.path}: {error}") from error
|
|
return self._parse(payload)
|
|
|
|
def _update(self, callback: Callable[[Value], tuple[Value, Outcome]]) -> Outcome:
|
|
try:
|
|
self.path.parent.mkdir(mode=0o700, parents=True, exist_ok=True)
|
|
with self.lock_path.open("a+", encoding="utf-8") as lock:
|
|
fcntl.flock(lock.fileno(), fcntl.LOCK_EX)
|
|
current = self.load()
|
|
updated, outcome = callback(current)
|
|
if updated != current:
|
|
self._write(updated)
|
|
return outcome
|
|
except self.error_type:
|
|
raise
|
|
except OSError as error:
|
|
raise self.error_type(f"cannot update {self.path}: {error}") from error
|
|
|
|
def _write(self, value: Value) -> None:
|
|
payload = self._serialize(value)
|
|
temporary_name: str | None = None
|
|
try:
|
|
with tempfile.NamedTemporaryFile(
|
|
mode="w",
|
|
encoding="utf-8",
|
|
dir=self.path.parent,
|
|
prefix=f".{self.path.name}.",
|
|
delete=False,
|
|
) as temporary:
|
|
temporary_name = temporary.name
|
|
json.dump(payload, temporary, ensure_ascii=False, indent=2)
|
|
temporary.write("\n")
|
|
temporary.flush()
|
|
os.fsync(temporary.fileno())
|
|
os.chmod(temporary_name, 0o600)
|
|
os.replace(temporary_name, self.path)
|
|
directory_fd = os.open(self.path.parent, os.O_RDONLY | os.O_DIRECTORY)
|
|
try:
|
|
os.fsync(directory_fd)
|
|
finally:
|
|
os.close(directory_fd)
|
|
finally:
|
|
if temporary_name is not None:
|
|
try:
|
|
Path(temporary_name).unlink(missing_ok=True)
|
|
except OSError:
|
|
pass
|